Engraving or etching words or images in stone objects, such as monuments, headstones, statuary and other stone ornaments or utilitarian items can be expensive and time consuming due to the scarcity of skilled stone carvers and the difficulty in accurately and consistently engraving or etching stone. Consequently, methods have been developed for sandblasting desired lettering or designs into a stone surface using stencils. For example, U.S. Pat. No. 3,194,153 to Rogerson discloses a rubber stencil for sandblasting memorial stones. The stencil is affixed to the stone surface is then sandblasted. The duration of the sandblasting determines the depth of the etching. The stencil protects the remainder of the stone so that only the desired letters or designs are etched into the stone surface. These rubber stencils have been used very successfully because the rubber provides the resilience necessary to withstand the harsh sandblasting environment and is thus very durable. This durability ensures that the stencil will remain intact during the sandblasting operation which in turn ensures that the letters or designs etched in the object are sharp.
Rubber stencils are, however, relatively expensive due to the high cost of natural rubber. This is due to the many difficulties inherent in processing natural rubber. Moreover, natural rubber stencils are difficult to cut precisely. Thus, efforts have been made to provide alternative materials for use in sandblasting stencils. For example, U.S. Pat. No. 3,473,941 to Hemphill discloses a resist material which may be silk-screened onto a fibrous panel such as an acoustic tile. The tile is then sandblasted to provide a textured surface. The resist is a vinyl compound made up of 100 parts resin, 100 parts plasticizer, 200 parts pigment and small amounts of stabilizers, surfactants and dispersants. Similarly, U.S. Pat. No. 3,267,621 to Meyers et al. discloses a mask for use in sandblasting glass in which a polyvinyl chloride (PVC) plastisol layer is applied directly to the glass. Both of these patents teach a stencil which is silk-screened directly to the article to be sandblasted. Thus, neither the Hemphill or Meyers et al. stencils can be removed for reuse. Moreover, in both cases, the article to be sandblasted is very fragile. Consequently, the sandblasting environment is substantially less severe than that encountered when sandblasting stone monuments. Because these stencils of Hemphill and Meyers are used only once and in relatively benign environments, those stencils need not be particularly resilient or durable.
Efforts to use PVC compounds in stencils for sandblasting stone monuments have failed because conventional formulations of PVC do not have the resilience of rubber. Consequently, previous PVC stencils suffered from "blow out," i.e., the PVC stencils wore excessively during sandblasting, resulting in etchings that were not sharp.